Medical treatment often requires the administration of a therapeutic agent (e.g., medicament, drugs, etc.) to a particular part of a patient's body. As patients live longer and are diagnosed with chronic and/or debilitating ailments, the likely result will be an increased need to place even more protein therapeutics, small-molecule drugs, and other medications into targeted areas throughout the patient's body. Some maladies, however, are difficult to treat with currently available therapies and/or require administration of drugs to anatomical regions to which access is difficult to achieve.
A patient's eye is a prime example of a difficult-to-reach anatomical region, and many vision-threatening diseases, including retinitis pigmentosa, age-related macular degeneration (AMD), diabetic retinopathy, and glaucoma, are difficult to treat with many of the currently available therapies. For example, oral medications can have systemic side effects; topical applications may sting and engender poor patient compliance; injections generally require a medical visit, can be painful, and risk infection; and sustained-release implants must typically be removed after their supply is exhausted (and generally offer limited ability to change the dose in response to the clinical picture).
Another example is cancer, such as breast cancer or meningiomas, where large doses of highly toxic chemotherapies, such as rapamycin, bevacizumab (e.g., Avastin), or irinotecan (CPT-11), are typically administered to the patient intravenously, which may result in numerous undesired side effects outside the targeted area. Other examples of difficult-to-reach anatomical regions for drug delivery include the knee, where drugs often have difficulty penetrating the avascular cartilage tissue for diseases such as osteoarthritis, the brain, and the spine.
Implantable drug delivery systems may include a refillable drug reservoir, a cannula for delivering the drug, etc., and generally allow for controlled delivery of pharmaceutical solutions to a specified target. This approach can minimize the surgical incision needed for implantation and typically avoids future or repeated invasive surgery or procedures. In a typical procedure, the pump is implanted using an instrument specifically adapted for the purpose.
Instruments (“introducers”) for surgically implanting medical devices tend to have limited capabilities, however. Many implants are difficult to maneuver due to the typically smooth design necessary for implantation in the body, and some devices currently used in surgery can cause damage to the delicate external components of the implant. Surgery may be postponed if the device is damaged by the instrument or slips outside the sterile field due to lack of grip on the device. Medical devices that are inserted into the body are often saturated in sterile water before implantation, further complicating the ability to grip an already smooth (and possibly rounded or even spherical) implant. Many implants also have parylene coatings on the outside, and this layer can also be damaged by contact with the introducer. Finally, polymeric introducers may be subject to buildup of electrostatic charge, which can damage an electronic implantable device.